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                                   BULLETIN
         FSB-100 - ANTIFOULING PAINT RECOMMENDATIONS FOR ALL RDI ADCPs
                            DATE/REV:  15AUG96 / 0
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ABSTRACT:  Describes the latest RDI recommendations for antifouling paints.

INSTRUMENT/PROGRAM AFFECTED:  All ADCP systems.

DESCRIPTION:  Objects deployed in shallow-water (within 100 meters [328 feet]
of the surface) are subject to biofouling, especially in warm water.  Biofoul-
ing is not usually a problem in deep water.  Soft-bodied organisms usually
cause no problems, but barnacles can cut through the urethane transducer face
causing failure of the transducer and leakage into the ADCP.  Therefore, you
should take steps to prevent biofouling during shallow-water deployments.

SOLUTION/ACTION:  RDI no longer recommends the use of Nopcocide for the pre-
vention of biofouling.  At present, we recommend the following antifouling
paint manufacturer, paint brand, and preparation procedures for all ADCPs.

    Courtalds Finishes                 Telephone:  908-686-1300
    Interlux brand paints              Web Page :  www.interlux.com

1-PROCEDURE FOR ALUMINUM INSTRUMENTS (usually DR/SC/CS/BW systems)

  a.  Metal Surfaces

      (1) Metal Surface Preparation

          (a) On bare aluminum metal, use 353/354 Vinylux solvent wash (thin
              with 355).  Perform the Metal Surface Application (Step (2),
              below) between 1 and 24 hours.
          (b) On painted surfaces, use 120-grit sandpaper to remove gloss.

      (2) Metal Surface Application

          (a) Mask as necessary.
          (b) Apply one or two coats of Trilux-2 (active ingredient is copper
              thiocyanate) at 4 mil/coat.  If applying a second coat, wait at
              least 12 hours to allow the first coat to dry.  One coat lasts
              one season (3-4 months); two coats might last one year.  NOTE: 
              Do NOT use cuprous oxide on or near aluminum systems.

  b.  Transducer Faces (urethane surfaces)

      (1) Urethane Surface Preparation - Lightly sand by hand with 120-grit
          paper.

      (2) Urethane Surface Application - Apply one or two coats of Trilux-2 at
          4 mil/coat.  If applying a second coat, wait at least 12 hours to
          allow the first coat to dry.  One coat lasts one season (3-4
          months); two coats might last one year.  NOTE:  Do NOT use cuprous
          oxide on or near aluminum systems.


2-PROCEDURE FOR BRASS AND BRONZE INSTRUMENTS (usually VM systems)

  a.  Metal Surfaces

      (1) Metal Surface Preparation

          (a) Sand metal surfaces with 60-grit paper to expose clean metal.
          (b) Clean surface with 353/354 Vinylux solvent (thin with 355 as
              needed).  Perform the Metal Surface Application (Step (2), be-
              low) between 1 and 24 hours.

      (2) Metal Surface Application

          (a) Apply a barrier coat of 360R Underwater Metal Primer to all
              exposed brass.  Allow the primer to dry for 5 to 8 hours before
              proceeding.
          (b) Mask as necessary to avoid having the cuprous oxide antifouling
              paint come in contact with any bare metal surfaces.
          (c) Apply cuprous oxide 669 antifouling paint as desired.  If more
              than one coat is used, allow each coat to dry for 16 hours.

  b.  Transducer Faces (urethane surfaces)

      (1) Urethane Surface Preparation - Lightly sand by hand with 120-grit
          paper.

      (2) Urethane Surface Application

          (a) Mask as necessary to avoid having the cuprous oxide antifouling
              paint come in contact with any bare aluminum surfaces.
          (b) Apply a thin barrier coat of 360R Underwater Metal Primer. 
              Allow the primer to dry for 5 to 8 hours before proceeding.
          (c) Apply cuprous oxide 669 antifouling paint.  Do not exceed the
              maximum thickness specified in Table 1.  If more than one coat
              is needed to reach the maximum thickness, allow each coat to dry
              for 16 hours.


      TABLE 1.  RECOMMENDED MAXIMUM THICKNESS OF CUPROUS OXIDE 669 PAINT

                System Frequency       Maximum Paint Thickness*
                ----------------       -----------------------
                     75 kHz              1.00 mm (0.040 in.)
                    150 kHz              0.50 mm (0.020 in.)
                    300 kHz              0.25 mm (0.010 in.)
                    600 kHz              0.10 mm (0.005 in.)
                   1200 kHz              Use Trilux-2 only.

      * NOTE:  Cuprous oxide 669 is a high-density paint.  As such,
      using it will slightly degrade ADCP performance.  Exceeding these
      recommended maximum thicknesses will further degrade performance.

CAUTIONS:
  1.  Read the Material Safety Data Sheet before using any of the listed sol-
      vents and paints.
  2.  Do not arbitrarily use antifouling paints for deep-water applications. 
      For shallow-water applications, using antifouling paints may be appro-
      priate if you cannot clean the ADCP regularly (weekly).  Be aware that
      antifouling paints can accelerate the corrosion of aluminum (usually
      DR/SC/CS/BW systems), and can initiate dezincification corrosion of
      brass (usually VM systems).  Once initiated, dezincification will rapid-
      ly destroy the transducer.
  3.  Some antifouling coatings may not be legal for use in all areas.  Check
      with your local environmental agency before using the antifouling paint.
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